SaaS model
There are 3 types of SaaS operation model.
Single Tenant
In a Software as a Service (SaaS) model, each of your customers are a tenant of your application. In the single tenant model, a single dedicated instance of an application is deployed for each customer. For example, with a N-tier architecture style application, all customers get a new dedicated instance of the web, middle, and data tiers. These tiers are not shared between these customers.
Mixed Tenant
In mixed tenant model, one or more parts of an application are deployed as dedicated for each customer, and the rest is shared between all customers. For example, with a N-tier architecture style application the web and middle tiers are shared between all customers. However, a dedicated data tier and database is provisioned for each customer.